In recent times, much thought has been given to alternative energy sources as a means to power automobiles. Petroleum based fuels, such as gasolines, are polluting and represent a finite energy source.
Electrically driven vehicles have many advantages over automobiles that run on fossil fuels. One of the major advantages of an electric car is the lack of exhaust pollutants. Another advantage is the reduction in the noise level of electrical vehicles over those driven by combustion engines.
One of the drawbacks to implementing electric cars as a viable alternative to present day combustion engine vehicles is the limited energy storage and supply provided by present, on-board battery systems. Storage batteries for automobiles must be able to supply enough power to drive an automobile for about 250 miles without recharging. Present day batteries, while not able to achieve this goal, are rapidly being improved. Continuous progress is being made in the on-board batteries needed to power the electric cars, and it is very likely that a practical battery system will be available in only a few years.
Another problem inherent with electric vehicle usage is the recharging of the vehicle's batteries on the road. If there are many electric vehicles in use, direct charging during daylight hours or during peak electric energy demand periods becomes a serious issue to today's electric utilities.
Recharging stations using banks of lead-acid storage batteries to recharge electric vehicles can draw and store electricity from power generation stations at night or during off-peak hours for subsequently supplying vehicles during the day. However, problems associated with lead-acid batteries include their generation of potentially explosive hydrogen gas, and their relatively short operational lifetimes. Thus, an electricity storage and charging station utilizing a lead-acid battery system would require a high degree of maintenance, and could potentially be a dangerous facility, if mismanaged.
In order to overcome many of the drawbacks of a battery storage system, the present invention proposes to store electrical energy utilizing capacitors. Any other suitable electricity storage mechanism can also be used without departing from the scope of the present invention. Capacitors are a particularly attractive alternative to battery storage, however, because they: (1) charge and discharge electricity quickly, (2) do not need maintenance, (3) have fairly low losses, and (4) feature long operational lives.
The present invention contemplates the use of many charging stations deriving their power from a central electrical generating source, such as an electrical power plant. Each charging station would use a control strategy for charging its electric energy storage means during low demand periods. This would be accomplished by means of a controller. The controller could facilitate simple off-peak charging, real-time-price-based control, and direct utility control. Moreover, each of the charging stations would be equipped with a plurality of bays or charging positions, each capable of charging a separate vehicle. The station charge controller would regulate the amount of power drawn by each charging station from the main generating source. Each vehicle bay would have a feedback control for measuring the state-of-charge of the vehicle storage system and for regulating and measuring the exact amount of energy discharged to the individual automobile. Measuring energy delivered to a vehicle can be used for billing purposes.
The ability to draw power during periods advantageous to the electric utility, to charge automobiles with exacting amounts of energy, as required, and to provide billing information, makes the aforementioned invention most attractive as a practical vehicular energy charging system.